A number of research and clinical procedures require the use of an array of wells or tubes in which multiple samples are placed for screening/evaluation. In general, these multi-well test plates may be classified as those having a single opening at the top through which samples are added and removed and those of the filter-type. The filtration devices have an opening at the top through which a sample is introduced and a second opening at the bottom which is fitted with a filter. These trays are used for a wide variety of biochemical and biological procedures such as polynucleotide amplification and the growth of cell cultures.
With respect to the filtration type plates, there are several conventional constructions. These devices generally have a filter medium which prevents the flow of the sample through the filter until the sample is placed under pressure, either through a positive pressure applied to the top of the plate or, more commonly, by the vacuum extraction of the sample through the filter. In the case of vacuum filtration with a multi-well plate, it is also known to use a gasket limited to the perimeter of the plate-manifold interface, creating a seal such that the vacuum is established more efficiently.
An important disadvantage in the use of a conventional array of tubes mounted within a plate, and with multi-well plates of conventional design (either with or without a filtration feature) is the problem associated with cross-contamination of the specimens. Most biological and biochemical assays and cell culture protocols must be performed with a high degree of stringency in terms of limiting contamination of the samples. Where multiple samples are processed in a confined area, such as an 8.times.12 format (96 well plate), the risk of cross-contamination between samples is significant. In the case of assays, this cross-contamination may lead to erroneous test results. If a single unitary plastic plate were used as a top or collective lid to close the tops of all the wells or tubes, an inadequate seal would be formed which could allow the migration of sample between wells during handling or simply through condensation and capillary processes. In addition, multi-well arrays which utilize individual stoppers or screw-type caps to close each well are unwieldy and allow the introduction of contaminants as reagents and the like are added to the wells during different stages of an analysis/experiment. This problem is particularly acute when snap-type caps are opened, which frequently produces an aerosol. The aerosol formation may result in cross-contamination between samples. In addition, aerosols may expose technicians to potentially pathogenic microorganisms and the like which may be present in the samples being analyzed. In addition, the conventional tube arrays and multi-well plates are not generally modular in construction. Although incorporated into a single plate, many of these conventional devices still function as discrete elements which are difficult to manipulate during use and often require a transfer of samples which provides additional risks of contamination.
Therefore, it is an object of the present invention to provide a tray assembly having an array of sample containment sites having a design which reduces the risk of cross-contamination between containment sites.
It is still another object of the present invention to provide a multi-well plate or tube array plate in which cross-contamination of samples is significantly reduced by providing a resilient gasket which isolates each containment site.
It is still a further object of the present invention to provide a modular multi-well plate in which a plurality of planar elements that define containment sites are separated by resilient gaskets such that each containment site is substantially isolated. The samples can be filtered without transferring the samples to a separate filtration device.
It is still a further object of the present invention to provide a sample containment assembly which eliminates the requirement of transferring samples between various apparatus during sample processing.
These and other objects and advantages of the present invention will be more fully understood with reference to the drawings.